Polymeric foam and scrim sheathings

ABSTRACT

A sheathing adapted to be fastened to at least one wall supporting structure comprises at least two layers. The first layer comprises a polymeric foam layer. The second layer comprises a polymeric scrim and is located adjacent to the first layer. The second layer has a first portion and a second portion. The second portion is located near the periphery of the polymeric scrim layer. The first portion has a first machine direction (MD) scrim count number and a first transverse direction (TD) scrim count number, and the second portion has a second MD scrim count number and a second TD scrim count number. At least one of the second MD scrim count number and the second TD scrim count number is greater than the respective first MD scrim count number or the first TD scrim count number so as to inhibit failure of the scrim.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 10/782,480, filed on Feb. 19, 2004, which is a continuation ofU.S. patent application Ser. No. 09/660,649, filed on Sep. 13, 2000,which is a Continuation-in-Part of U.S. patent application Ser. No.09/421,031, filed on Oct. 20, 1999, now U.S. Pat. No. 6,536,176 B1.These related applications are hereby incorporated by reference in theirentirety.

FIELD OF THE INVENTION

The present invention relates generally to sheathings that are used instructures and, more particularly, to polymeric foam sheathing materialsthat are used in prefabricated housing, site built housing, andremodeling.

BACKGROUND OF THE INVENTION

There are different commercial sheathings that are used in theconstruction of buildings. Sheathings include materials that span theframe supports of buildings. Some of the commercial products that havebeen used as sheathing include thin composite laminations, fiberboard,orientated strand board (OSB) and plywood. Some of these productsprovide structural strength, durability and/or rigidity. These products,however, have disadvantages such as being heavy and difficult toinstall, providing little insulation and/or having poor moistureresistance.

There are other commercial products that are available as sheathing. Forexample, polyisocyanurate foam, extruded polystyrene foam, and moldedexpanded polystyrene (EPS) foam. These existing foamed materialsgenerally have advantages such as increased insulation and easierhandling. These existing foamed materials, however, have disadvantagessuch as their lack of strength as measured by wind resistance. This isshown, for example, by their failures to withstand 100 miles per hourwinds when installed. Lack of wind resistance may cause problems such asfracturing, cracking and/or edge pull out of the sheathing from thefasteners. During the pulling of the edge of the material, the fastenergenerally remains, but the sheathing is pulled away.

Existing foam sheathing is still susceptible to damage at the buildingsite prior to installation. This problem is further evident when, forexample, delays occur in the installation and/or the installation occursin extreme weather conditions. One common example of damage that mayoccur is when a piece breaks off from a remainder of the sheathingduring the process of installation or by vandalism after installation atthe building site before being covered with an exterior facing such assiding, brick, or stucco.

Accordingly, a need exists for a sheathing material for use inprefabricated housing, site built housing, and remodeling that overcomesthe above-noted shortcomings associated with existing sheathing.

SUMMARY OF THE INVENTION

According to one embodiment of the present invention, a sheathingadapted to be fastened to at least one wall supporting structurecomprises at least two layers. The first layer comprises a polymericfoam layer. The second layer comprises a polymeric scrim and is locatedadjacent to the first layer. The second layer has a first scrim portionand a second portion. The second portion is located near the peripheryof the polymeric scrim layer. The first portion has a first machinedirection (MD) scrim count number and a first transverse direction (TD)scrim count number, and the second portion has a second MD scrim countnumber and a second TD scrim count number. At least one of the second MDscrim count number and the second TD scrim count number is greater thanthe respective first MD scrim count number or the first TD scrim countnumber so as to inhibit failure of the scrim.

According to another embodiment, a sheathing adapted to be fastened toat least one wall supporting structure comprises at least two layers.The first layer comprises a polymeric foam layer and is located adjacentthe second layer. The second layer comprises a polymeric scrim having auniform scrim count number. The polymeric scrim has a machine direction(MD) scrim count number which is least 18 and a transverse direction(TD) scrim count number which is at least 4 so as to inhibit failure ofthe scrim.

According to another embodiment of the present invention, a sheathingadapted to be fastened to at least one wall supporting structurecomprises at least three layers. The first layer comprises a polymericfoam layer. The second layer comprises a polymeric scrim and has a firstportion and a second portion. The second portion is located near theperiphery of the polymeric scrim layer. The first portion has a firstmachine direction (MD) scrim count number and a first transversedirection (TD) scrim count number, and the second portion has a secondMD scrim count number and a second TD scrim count number. At least oneof the second MD scrim count number and the second TD scrim count numberis greater than the respective first MD scrim count number or the firstTD scrim count number so as to inhibit failure of the scrim. The thirdlayer comprises an impact polystyrene and is located between the firstand the second layers.

According to one method of the present invention, a sheathing isprovided that comprises at least two layers. The first layer comprises apolymeric foam layer. The second layer comprises a polymeric scrim andis located adjacent to the first layer. The second layer has a firstportion and a second portion. The second portion is located near theperiphery of the polymeric scrim layer. The first portion has a firstmachine direction (MD) scrim count number and a first transversedirection (TD) scrim count number, and the second portion has a secondMD scrim count number and a second TD scrim count number. At least oneof the second MD scrim count number and the second TD scrim count numberis greater than the respective first MD scrim count number or the firstTD scrim count number so as to inhibit failure of the scrim. Thesheathing is installed to a wall supporting structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of a two-layer sheathing according to oneembodiment of the present invention.

FIGS. 2 a and 2 b show front views of the second layer of the sheathingaccording to two embodiments of the present invention.

FIG. 3 shows a side view of a three-layer sheathing according to anotherembodiment of the present invention.

FIG. 4 shows a side view of a four-layer sheathing according to anotherembodiment of the present invention.

FIG. 5 shows a side view of a five-layer sheathing according to yetanother embodiment of the present invention.

FIG. 6 shows a side view of a seven-layer sheathing according to afurther embodiment of the present invention.

FIG. 7 shows a cut-away perspective view of a five-layer sheathingfastened to a wall supporting structure according to one embodiment ofthe present invention using the second layer embodiment depicted in FIG.2 a.

FIG. 8 shows a schematic flow diagram of an overall sequence ofoperations according to one process involved in the manufacture of athree-layer sheathing such as that shown in FIG. 3.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and will herein be described in detail. Itshould be understood, however, that it is not intended to limit theinvention to the particular forms disclosed but, on the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by theappended claims.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Turning now to the drawings and referring initially to FIG. 1, atwo-layer sheathing 10 is shown according to one embodiment of thepresent invention. The sheathings of the present invention, includingsheathing 10, are adapted to be fastened to a wall supporting structure.On a building, sheathings are typically covered by an exterior facingsuch as siding, brick or stucco. The sheathing 10 of FIG. 1 comprises apolymeric scrim layer 12 and a polymeric foam layer 14. The polymericscrim layer 12 of the present invention provides additional strength anddurability to the polymeric foam layer 14. Polymeric Scrim Layer Thepolymeric scrim layer 12 may be made of woven material or non-wovenmaterial. Woven material is generally defined as long fibers that areintertwined to produce a material. Non-woven material is generallydefined as randomly joined fibers that are bonded or pressed together byadhesive or other means. The randomly joined fibers that form non-wovenmaterial are typically shorter than those used in forming wovenmaterial. The woven material is generally preferred because it providesan excellent strength to weight ratio that is desirable inwind-resistant applications.

One type of woven scrim that may be used in polymeric scrim layer 12 isa scrim that runs in the machine direction (MD) and the weft ortransverse direction (TD). For example, a scrim having a scrim count of28×4 indicates that the scrim has 28 cords, filaments, or strands perinch in the machine direction and 4 cords, filaments, or strands perinch in the transverse direction. A scrim having cords that run in themachine direction and the weft or transverse direction is commonlyreferred to as a cross-woven scrim. This type of woven scrim may be thetype that is commonly used in applications such as carpet backing.

FIGS. 2 a and 2 b depict embodiments of respective polymeric scrimlayers 112, 212 according to the present invention. As depicted in FIG.2 a, the polymeric scrim layer 112 has a first portion 102 and a secondportion 104. The first portion 102 is located in the central area of thepolymeric scrim layer 112 while the second portion 104 is located nearthe periphery of the polymeric scrim layer 112. The second portion 104extends from the periphery of the polymeric scrim layer 112 inwardlytoward the central portion of the polymeric scrim layer 112.

The first portion 102 has a first machine direction (MD) scrim countnumber running in the machine direction 108 and a first transversedirection (TD) scrim count number running in the transverse direction110. Similarly, the second portion 104 has a second MD scrim countnumber running in the machine direction 108 and a second TD scrim countnumber running in the transverse direction 110. At least one of thesecond MD scrim count number and the second TD scrim count number isgreater than the respective first MD scrim count number or the first TDscrim count number. By increasing the scrim count at the periphery ofthe polymeric scrim layer 112, the periphery of the polymeric scrimlayer 112 is reinforced and inhibits the scrim from unraveling.

As depicted in FIG. 2 a, the polymeric scrim layer 112 may also includea third portion 106. The third portion 106 is located near the peripheryof the polymeric scrim layer 112 opposite the second portion 104. Thethird portion 106 extends from the periphery of the polymeric scrimlayer 112 inwardly toward the central portion of the polymeric scrimlayer 112. The third portion 106 has a third MD scrim count numberrunning in the machine direction 108 and a third TD scrim count numberrunning in the transverse direction 110. At least one of the third MDscrim count number and the third TD scrim count number is greater thanthe respective first MD scrim count number or the first TD scrim countnumber. Optionally, the second and third MD scrim count numbers are thesame, and the second and third TD scrim count numbers are the same.

As depicted in FIGS. 2 a and 2 b, the second and third MD scrim countnumbers vary. The MD scrim count number, however, can be varied basedupon the desired use of the sheathing and the cost. FIG. 2 a depicts anembodiment where the second MD scrim count number is the same at thethird MD scrim count number and the second and third MD scrim countnumbers are at least two times the first MD scrim count number. Thesecond and third MD scrim count numbers can range from at least twotimes, at least four times, and to at least six times the first MD scrimcount number.

FIG. 2 b depicts another embodiment of the polymeric scrim layer 212according to the present invention. Polymeric scrim layer 212 has afirst portion 202, a second portion 204 and a third portion 206. Thefirst portion 202 is located in the central area of the polymeric scrimlayer 212. The second and third portions 204, 206 are located near theperiphery of the polymeric scrim layer 212 on opposing sides. The firstportion 202 has a first MD scrim count number in the machine direction208 and a first TD scrim count number in the transverse direction 210.The second portion 204 has a second MD scrim count number in the machinedirection 208 and a second TD scrim count number in the transversedirection 210. The third portion 206 has a third MD scrim count numberin the machine direction 208 and a third TD scrim count number in thetransverse direction 210. FIG. 2 b depicts an embodiment where thesecond and third MD scrim count numbers are the same and the second andthird MD scrim count numbers are at least six times the first MD scrimcount number.

The distance that the second and third portions extend from theperiphery of the polymeric scrim layer 112, 212 varies. The second andthird portions generally extend from the periphery of the polymericscrim layer 112, 212 about ½ of an inch to about 3 inches. The secondand third portions preferably extend from the periphery of the polymericscrim layer 112, 212 about ½ of an inch to about 1 inch.

The second portion 104, 204 is preferably located on at least twoopposing portions of the periphery of the polymeric scrim layer 112,212. It is preferred that the second portion extends along two entiresides of the polymeric scrim layer 112, 212. It is also contemplatedthat the third portion 106, 206 may be located on one or more of thesides of the polymeric scrim layer 112, 212 rather than the secondportion 104, 204. The second and third portions are located generallyparallel to the wall supporting structure.

It is contemplated that various scrim counts may be used in forming thepolymeric scrim layer having an increased scrim count at the periphery.Examples of suitable scrim counts that may be used in the centralportion of the polymeric scrim layer having an increased scrim count atthe periphery include 7×4, 8×6, 9×4, 21×4, 24×4, 28×4, 18×6, and 21×6.It is contemplated that the scrim count number at the periphery of thepolymeric layer will be greater than the scrim count number in thecentral portion and that the selection of the scrim count number at theperiphery will vary based on the desired use of the sheathing and thecost.

According to another embodiment, the polymeric scrim layer has a uniformscrim count number so as to inhibit failure of the scrim. According tothis embodiment, the polymeric scrim layer has an MD scrim count numberwhich is least 18 and a TD scrim count number which is at least 4.Examples of suitable scrim counts that may be used where the polymericscrim layer has a uniform scrim count number include 21×4, 24×4, 28×4,18×6, and 21×6.

The polymeric scrim layer 12 may be made of materials such aspolyolefins, polyesters and nylons. Polyolefins that may be used in thepolymeric scrim layer 12 include polypropylenes or polyethylenes. Theterm “polypropylene” as used herein includes polymers of propylene orpolymerizing propylene with other aliphatic polyolefins, such asethylene, 1-butene, 1-pentene, 3-methyl-1-butene, 4-methyl-1-pentene,4-methyl-1-hexene, 5-methyl-1-hexene and mixtures thereof. Polypropylenenot only includes homopolymers of propylene, but also propylenecopolymers comprised of at least 50 mole percent (preferably at least 70mole percent) of a propylene unit and a minor proportion of a monomercopolymerizable with propylene and blends of at least 50 percent byweight of the propylene homopolymer with another polymer.

The term “polyethylene” as used herein includes low density polyethylene(LDPE), medium density polyethylene (MDPE), high density polyethylene(HDPE), very low density polyethylene (VLDPE), linear low densitypolyethylene (LLDPE), metallocene-catalyzed linear low densitypolyethylene (mLLDPE) and combinations thereof.

LDPE is generally defined as an ethylenic polymer having a specificgravity of from about 910 to about 925 kg/m³. MDPE is generally definedas an ethylenic polymer having a specific gravity between the LDPEs andthe HDPEs (i.e., from about 925 to about 940 kg/m³). The high densitypolyethylene (HDPE) of the present invention has a specific gravity offrom about 940 to about 970 kg/m³. The term polyethylene as used hereinincludes homopolymers of ethylene and copolymers comprised of at least50 mole percent of a ethylene unit (preferably at least 70 mole percent)and a minor (i.e., less than 50%) proportion of a monomercopolymerizable with the ethylene unit. The term LDPE as used hereinalso includes physical blends of two or more different homopolymers thatare classified as LDPEs. Similarly, the term MDPE and HDPE may alsoinclude blends of two or more different homopolymers classified as MDPEsand HDPEs, respectively.

The VLDPE resins have densities ranging from about 880 to about 912kg/m³, more commonly from about 890 to about 910 kg/m³, and melt indicesof from about 0.5 to about 5 g/10 min., and from about 1 to about 3 g/10min.

The LLDPE of the present invention generally has from about 1 to about20, preferably from about 1 to about 10 weight percent of said higheralpha olefin monomer copolymerized therein. In addition, the alphaolefin monomer employed in the ethylenic copolymer may be selected fromthe group consisting of 1-butene, 3-methyl-1-butene, 3 methyl-1-pentene,1-hexene, 4-methyl-1-pentene, 3-methyl-1-hexene, 1-octene and 1-decene.The LLDPE resins that may be used in the present invention havedensities ranging from about 890 to about 940 kg/m³, more commonly fromabout 900 to about 930 kg/m³, and a melt index (I₂) of from about 1 toabout 10 g/10 min. as determined by ASTM D1238.

The metallocene-catalyzed polyethylene (mLLDPE) is a polymer having alow polydispersity. The low polydispersity polymer may be prepared froma partially crystalline polyethylene resin that is a polymer preparedwith ethylene and at least one alpha olefin monomer, e.g., a copolymeror terpolymer. The alpha olefin monomer generally has from about 3 toabout 12 carbon atoms, preferably from about 4 to about 10 carbon atoms,and more preferably from about 6 to about 8 carbon atoms. The alphaolefin comonomer content is generally below about 30 weight percent,preferably below about 20 weight percent, and more preferably from about1 to about 15 weight percent. Exemplary comonomers include propylene,1-butene, 1-pentene, 1-hexene, 3-methyl-l-pentene, 4-methyl-1-pentene,1-octene, 1-decene, and 1-dodecene.

The low polydispersity polymer has a density of from about 880 to about940 kg/m³. The polydispersity polymer generally have a molecular weightdistribution, or polydispersity, (M_(w)/M_(n), “MWD”) within the rangeof from about 1 to about 4, and more typically from about 2 to about 3.The melt flow ratio (MFR) of these polymers, defined as I₂₀/I₂ and asdetermined in accordance to ASTM D1238, is generally from about 12 toabout 22 and typically from about 14 to about 20. The melt index (MI),defined as the I₂ value, should be in the range of from about 0.5 toabout 10 g/10 min. and typically from about 1 to about 5 g/10 min. asdetermined by ASTM D1238.

An example of a “polyester” includes a polyester resin which is apolycondensation product of a dicarboxylic acid with a dihydroxyalcohol. An example of a “polyethylene terephthalate” includes apolyester resin made from ethylene glycol and terephthalic acid. Anexample of a “nylon” is a polyamide polymer that is characterized by thepresence of the amide group (—CONH).

It is contemplated that additional polymeric scrim layer(s) can be addedto the sheathing. For example, the sheathing may include polymeric scrimlayers on opposing sides of the polymeric foam layer.

Polymeric Foam Layer

The polymeric foam layer 14 is located adjacent to the scrim layer 12 inFIG. 1. The polymeric foam layer 14 may be made from alkenyl aromaticresins, such as polystyrenic resin(s), and polyesters such aspolyethylene terephthalates. The term “alkenyl aromatic polymer” as usedherein includes polymers of aromatic hydrocarbon molecules that containan aryl group joined to an olefinic group with only double bonds in thelinear structure. The polymeric foam layer 14 may also be made frompolyolefinic resins such as LDPEs, HDPEs, LLDPEs, and the like. Thepolymeric foam layer 14 is preferably made from a polystyrenic resin(s),such as a general purpose polystyrene, because of economicalconsiderations at the present time. The polymeric foam layer 14,however, may be made from other polystyrenic resins such as impactpolystyrenes. The impact polystyrenes that are generally used includemedium impact polystyrenes and high impact polystyrenes. The polymericfoam layer 14 may also be made from a combination of virgin and/orreprocessed material. The polymeric foam layer 14, however, may also bemade from polyisocyanurate foam.

The polymeric foam layer 14 and the polymeric scrim layer 12 may bebonded by attaching, adhering, fusing or the like. For example, thepolymeric foam layer 14 and the polymeric scrim layer 12 may bethermally bonded to each another depending on the selected materials forforming the layers 12 and 14. Thermal bonding may be accomplished byconventional methods, such as a flameless air torches, heated rolls,radiant heaters and infrared heating.

Adhesive and Other Layers

Alternatively, the polymeric foam layer 14 and the polymeric scrim layer12 may be attached with an adhesive layer. This is shown in FIG. 3 wheresheathing 30 includes a polymeric scrim layer 12, a polymeric foam layer14 and an adhesive layer 16. The optional adhesive layer 16 is locatedbetween the polymeric scrim layer 12 and the polymeric foam layer 14.One type of adhesive that may be used is ethylene vinyl acetate (EVA).For example, modified EVAs such as BYNEL® made by DuPONT(® or Plexar®made by Equistar Chemicals may be used. These modified EVAs have meltindices generally from about 6.4 to about 25 g/10 min. as measured byASTM D1238and densities generally from about 923 to about 947 kg/m³ asmeasured by ASTM D1505. BYNEL® is an adhesive that is designed to bondmaterials that would not ordinarily adhere to each other.

Other adhesives that may be used include block copolymers that comprisepolymeric regions of styrene-rubber-styrene. For example, KRATON® madeby Shell(® Chemical Company may be used. Other adhesives arecontemplated in the present invention to bond the polymeric scrim layer12 to the polymeric foam layer 14.

Additional layers are contemplated in the sheathings of the presentinvention. For example, FIGS. 4, 5 and 6 depict a four-layer sheathing,a five-layer sheathing and a seven-layer sheathing, respectively.Referring specifically to FIG. 4, sheathing 40 includes a polymericscrim layer 12, a polymeric foam layer 14, an adhesive layer 16 and animpact polystyrenic layer 18. The polystyrenic layer 18 is preferablymade from a high impact polystyrene because of its desired stiffness.The polystyrenic layer 18 may be biaxially orientated so as to provideadditional durability and flexibility.

FIG. 5 depicts a sheathing 50 that is similar to the sheathing 40 ofFIG. 4 except that the sheathing 50 includes an additional impactpolystyrenic layer 18. Sheathing 60 of FIG. 6 comprises the same fivelayers of the sheathing 50 of FIG. 5. The sheathing 60 of FIG. 6,however, also comprises two additional layers. Specifically, thesheathing 60 includes an additional adhesive layer 16 and a polymericfilm layer 20. To provide additional strength and durability, thepolymeric film layer 20 may be made from a polyolefin(s) such aspolypropylene.

Other layers are contemplated for the sheathings of the presentinvention. For example, the sheathings of the present invention mayinclude radiant barrier layers or flame retardant layers.

Properties of the Sheathing

The sheathings of the present invention generally have a flexuralstrength of at least 100 lbs./in.², preferably at least 150 lbs./in.²and most preferably at least 200 lbs./in.² as measured by ASTM D1307.The sheathings of the present invention have excellent strength so as toprovide resistance to high winds. The sheathings of the presentinvention preferably satisfy the structural design requirements as setforth in the H.U.D. Guide for Manufactured Home Standards Programs (9thedition, Dec. 1994) for Wind Zone II conditions (a design wind speed of100 miles per hour) taken from § 3280.305(c) of the Federal Register.The sheathings also preferably satisfy the structural designrequirements as set forth in H.U.D. Guide for Manufactured HomeStandards Programs (9th edition, Dec. 1994) for Wind Zone III conditions(a design wind speed of 110 mph) taken from § 3280.305(c) of the FederalRegister.

The sheathings of the present invention may be formed into a number ofshapes. For example, the sheathing may be a flat sheet or a folded orhinged board (typically referred to as a fanfolded sheathing). Thefanfold sheathing is designed to unfold at its hinges and includes anumber of individual panels.

The sheathings of the present invention may be manufactured in a varietyof sizes. Popular sizes used in the housing market include a 4 foot by 7foot (4′×7′), 4′×7½′, 4′×8′ and 4′×9′ flat sheets. Other popular sizesin the housing market include a 4′×50″ fanfolded sheathing whichincludes a number of individual panels. If a fanfolded sheathing isused, it is preferred to have cross-members in the wall supportingstructure for which the fanfolded sheathing may be attached.

The thickness of the sheathings may also vary. The thickness of thesheathing is generally from about ¼ of an inch to about 3 inches asmeasured by ASTM C303. The thickness of the sheathing is preferably fromabout ¼ of an inch to about ¾ of an inch as measured by ASTM C303.

The layers of the sheathings typically vary in their respective weightpercent relative to each other. The sheathings generally comprise fromabout 2 wt.% to about 30 wt.% of the polymeric scrim layer(s) 12. Thesheathings generally comprise from about 25 wt.% to about 99 wt.% of thepolymeric foam layer(s) 14. The sheathings generally comprise from 0wt.% to about 15 wt.% of the adhesive layer(s) 16. It is contemplatedthat the remainder of the sheathings may include other optional layers.The sheathings generally comprise from 0 wt.% to about 50 wt.% of theimpact polystyrenic layer(s) 18 and from 0 wt.% to about 50 wt.% of thepolymeric film layer(s) 20.

The sheathings preferably comprise from about 2 to about 25 wt.%, andmost preferably from about 4 wt.% to about 20 wt.% of the polymericscrim layer(s) 12. The sheathings preferably comprise from about 30 toabout 95 wt.%, and most preferably from about 40 wt.% to about 90 wt.%of the polymeric foam layer(s) 14. Preferably, the sheathings comprisefrom about 1 to about 10 wt.%, and most preferably from about 1 wt.% toabout 7 wt.% of the adhesive layer(s) 16. The sheathings preferablycomprise from about 5 to about 35 wt.%, and most preferably from about 5wt.% to about 30 wt.% of the impact polystyrenic layer(s) 18. Thesheathings preferably comprise from 0 to about 25 wt.%; and mostpreferably from 0 wt.% to about 20 wt.% of the polymeric film layer(s)20.

The sheathings of the present invention may be used in various buildingssuch as prefabricated housing (also referred to as manufacturedhousing), site built housing, and remodeling. The sheathing may beinstalled to a wall supporting structure. An example is shown in FIG. 7where a sheathing 52 is installed to a plurality of wall supportingstructures 22 using the polymeric scrim layer 112 of FIG. 2 a. Thesheathing 52 a has been cut-away to depict the various layers 112, 14,16 and 18, while sheathing 52 b has not been cut-away in FIG. 7. FIG. 7also shows siding 56 being located on an exterior surface of thesheathing 52.

The sheathing 52 of FIG. 7 may be installed to the plurality of wallsupporting structure 22 by the use of fasteners (not shown). Thefastener may be a mechanical fastener such as a staple or nail.According to the embodiment depicted in FIG. 7, the polymeric scrimlayer 112 of the sheathing 52 includes a first portion 102, a secondportion 104, and a third portion 106 opposite the second portion 104.The second and third portions 104, 106 are located generally parallel tothe wall supporting structure 22.

It is contemplated that the sheathing of the present invention may beused in a roofing application to provide additional strength, to resistwind uplift and to provide durability that minimizes breakage duringhandling and installation. The sheathing may be used as an underlaymentfor low slope roofs.

PROCESS OF THE PRESENT INVENTION

According to one process of the present invention, a polymeric web offoam is provided to form the polymeric foam layer. The process may use asingle twin screw extruder or a tandem foam extrusion line. For example,the process begins by loading pellets of a polymeric resin(s) such aspolystyrenic foam resin. The polymeric resins in their solid form areadded into an extrusion hopper.

A nucleating agent (also referred to as cell size control agent) orcombination of such nucleating agents may be employed in the process ofthe present invention for advantages such as their capability forregulating cell formation and morphology. The amount of nucleating agentto be added depends upon the desired cell size, the selected blowingagent and the density of the polymeric composition. Known nucleatingagents such as talc, mixtures of sodium bicarbonate and citric acid, andthe like may be employed in the present invention.

It is contemplated that stability control agent(s) may also be added tothe polymeric resin(s), including conventional stability control agents.Some examples of stability control agents that may be used include, butare not limited to, glycerol monostearate, saturated higher fatty acidamides and glycerol monoester of a C₂₀-C₂₄ fatty acid.

If desired, fillers, colorants, light and heat stabilizers,plasticizers, chemical blowing agents, flame retardants, foamingadditives and plastic compounding agents may be added to the polymericcomposition. The polymeric composition comprises the polymeric resinand, if added, the nucleating agent, the stability control agent andadditives. The polymeric composition is conveyed through a feed zone ofthe extruder and heated at a temperature sufficient to form a polymericmelt.

A physical blowing agent may be added at the injection port area of theextruder in an appropriate ratio to the target density. The selectedblowing agent may be any type that is capable of producing foam with theselected resin. Some examples of blowing agents include physical blowingagents such as halocarbons, hydrocarbons or combinations thereof.Examples of these include commercially available hydrofluorocarbons,such as HFC-152a and HFC-134a, hydrochlorofluorocarbons, such as HCFC-22or HCFC-142b, and the C₃-C₆ hydrocarbons. Other types of blowing agentsinclude carbon dioxide. The polymeric composition and the selectedblowing agent are thoroughly mixed within the extruder in a mixing zoneand subsequently cooled in a cooling zone. The cooled polymeric-blowingagent melt is extruded thorough a die.

One method of the present invention for making a three-layer sheathingis shown in a schematic flow diagram in FIG. 8. In the process of FIG.8, the polymeric foam is extruded from an extruder 70 through a rounddie 72. After exiting the round die 72, the extrudate expands whenentering a lower pressure region (e.g., the atmosphere) and forms apolymeric web of foam. The polymeric web of foam is stretched over asizing mandrel 74 to size and then is slit to form the web of foam. Thepolymeric web of foam will eventually be used in forming the polymericfoam layer 14.

At least one of the outer surfaces of the polymeric web of foam istypically cooled so as to form a “skin.” The skin is typically about afew thousands (or a few mils) thick, but may vary depending on thecooling employed. The skin provides additional strength and alsoprovides a smoother surface that is more aesthetically pleasing to aconsumer if the polymeric layer is visible to the customer. It iscontemplated that cooling methods may be accomplished by using air andwater. The skinning may be performed, for example, by stretching thepolymeric foam of web 76 over the sizing mandrel 74 with optionalcooling wherein either surface of the polymeric foam of web 76 iscooled. It is contemplated that one or more of the surfaces of thepolymeric web of foam may be cooled.

The polymeric foam web 76 proceeds to travel around a S-wrap of rollers78 a-c in which roller 78 a is an idler roller and rollers 78 b and 78 care driven or pull rollers. The driven rollers 78 b, 78 c assist inmoving the polymeric foam web 76 through the process of the presentinvention. The polymeric foam web 76 proceeds between two driven rollers80 a,b. Driven rollers 80 a,b assist in maintaining a consistent surfaceon which a web of adhesive 82 a is added via an adhesive coating or alaminating machine 82. The adhesive machine 82 may be any conventionalmachine that is capable of applying the adhesive web 82 a to thepolymeric foam web 76. The adhesive machine 82 may coextrude the web ofadhesive 82 a with a second web, such as a web of impact polystyrene(not shown).

At the about the same time, a web of scrim 84 a is added via a rollunwind cart system 84. The cart system 84 may include an edge alignmentsystem to properly align the web of scrim 84 a to the polymeric foam web76. After exiting the driven rollers 80 a,b, the polymeric foam web 76,the web of adhesive 82 a, and the web of scrim 84 a form a sheathing web86.

It is contemplated that the sheathing web 86 may be processed to includeprinting on one or more surfaces or other treatments. The process ofFIG. 8 includes an optional printer 88 that prints on one surface of thesheathing web 86. It is contemplated that the printing may occur on thepolymeric foam web 76 before the webs of adhesive and scrim are added tothe polymeric foam web 76. The sheathing web 86 proceeds around a seriesof rollers 90 a-90 d and then to an optional edge trim system 92. Theedge trim system assists in sizing the sheathing web 86 to be used informing the sheathing of the present invention.

As shown in FIG. 8, the sheathing web 86 proceeds through an optionalperforating creasing machine 94. The perforating creasing equipment 94may include any conventional equipment that is capable of folding thesheathing web 86 of the present invention into a fanfold sheathing web.Of course, if flat sheathing is desired, the creasing equipment 94should not be included in the process. A perforating machine, however,may be used in producing a flat sheathing. The sheathing web is then cutto a desired dimension by shearing equipment 96. The shearing equipment96 may be any equipment capable of cutting the sheathing web 86 intodesired dimensions. It is also contemplated that other finishingoperations may occur such as stacking, counting, packaging and trimming.It is also contemplated that various measurements may be takenthroughout the process to ensure consistent measurements.

According to a second process of the present invention (not shown),additional layers may be added in forming other sheathings, such asthose described above. For example, a machine (not shown) may be addedto the process of FIG. 8 that is adapted to add an additional impactpolystyrenic web to the polymeric web of foam.

EXAMPLES Example 1

Negative wind pressure load tests were conducted on samples of sheathing(“Sheathing 1”) using a 2×4 (1 ½ inches×3 ½ inches) stud wall supportingstructure. Sheathing 1 had dimensions of 48 inches by 90 inches(48″×90″). Sheathing 1 consisted of five layers with the first layerbeing a woven polypropylene scrim having a scrim count of 28×4. Thesecond layer was made of a BYNEL® adhesive. The third and fifth layerswere made of high impact polystyrene. The second layer was locatedbetween the first and third layers. The fourth layer was a polystyrenefoam and was located between the third and fifth layers. This is asimilar structure as shown above in FIG. 7. The following describes thetest specimens that were used in Example 1.

Example 1 Specimen Description

A. Materials

-   -   1. Stud: Double 2×4, Stud Grade spruce pine fur (SPF) spaced at        16″ on center (o.c.)    -   2. Top Plate: Single 1×4, Ungraded SPF    -   3. Bottom Plate: Single 1×4, Ungraded SPF    -   4. Gypsum: 5/16″×48″×90″ Georgia Pacific    -   5. Siding: Georgia Pacific 4.5 Lap Vinyl Siding with a nailing        flange thickness of 0.036 inch    -   6. Adhesive: PVA

B. Fastening

-   -   Top plate attached to studs with three (3)- 7/16″×1 ¾″×15 gauge        (Ga.) Staples.    -   Bottom plate attached to studs with three (3)- 7/16″×1 ¾″×15 Ga.        Staples.    -   Sheathing 1 fastened with 1″×1 ½″×16 Ga. staples at 3″ o.c. on        single framing members.    -   Gypsum fastened to studs with 3/16″×1″×19 Ga. staples at 16″        o.c. per strip of siding.    -   Gypsum glued to frame with a ⅜″ bead of PVA glue on all framing        members.    -   Siding fastened to Sheathing 1 into the studs with 7/16″×1 ½″×16        Ga. staples at 16″ o.c. per strip of siding.

C. Construction

The 48″×90″ test sample was first assembled with 2×4 studs that were87.75 inches long. The top and bottom plates were 49.5 inches long.Polyethylene sheeting (6 mil) was placed between the 2×4 framing andSheathing 1. The framing was then squared with Sheathing 1 and fastenedas described above. The horizontal vinyl siding was fastened throughSheathing 1 and into the studs. The 5/16″ gypsum was then fastened tothe opposite side of the frame as described above. Glue was allowed tocure for 7 days before the testing began. Materials for the assembliestested were commercially purchased products.

Example 1 Test Setup and Procedure

The testing was conducted in accordance with the ultimate load testprocedures in H.U.D. Guide for Manufactured Home Standards Programs (9thedition, Dec. 1994) taken from § 3280.401(b) of the Federal Register. An11-¼″ deep wood box was built 1″ wider and 1″ longer than the testsample. The top and bottom plates of the test samples were secured to2×4 ledgers. The test samples were placed vertically on the test fixturewith the vinyl siding facing down and the ledgers bearing on top of thewood box. The polyethylene sheeting (6 mil) that was placed between thewall framing and Sheathing 1 was sealed to the table. This allowed theentire surface of Sheathing 1 to be exposed to the full negative loads.

The uniform load was applied by evacuating the air below the testspecimen using a vacuum pump. The applied load was measured with a watermanometer capable of reading in 0.1 inch increments. The load wasapplied in approximate ¼ design live load increments at 10 minuteintervals until 1.25 times design load was reached. The load was thenincreased to 2.5 times design load or until failure occurred. The loadin inches of water column was converted to pounds per square foot (psf)by using the conversion of 1 inch (of water column) to 5.2 psf.

Deflection readings were taken using dial indicators capable of readingin 0.001″ increments. The deflections were taken at the quarter-pointsof the center stud.

Example 1 Results

Three specimens (S1, S2, and S3) using 5/16″ Georgia Pacific Gypsum weretested for corner Wind Zone III requirements. The product sold byGeorgia Pacific Corporation that was used was 5/16″ PreDeck® GypsumBoard. The ultimate load in pounds per square foot (psf) was determinedin accordance with H.U.D. Guide for Manufactured Home Standards Programs(9th edition, Dec. 1994) taken from § 3280.401(b) of the FederalRegister. The average of these three specimens is shown under the “AVG.”column. The results are as follows in Table 1. TABLE 1 ULTIMATE EXPER.LOAD (PSF) AVG. DEFLECTION NO. S1 S2 S3 (PSF) (PASS/FAIL) WINDZONE 1 156150.8 161.2 156 PASSED III Corner

The samples in Experiment 1 satisfied the ultimate load under a cornercondition for Wind Zone III. In addition, the samples in Experiment 1also passed the deflection test under a comer condition for Wind ZoneIII. The ultimate load requirement for Wind Zone III for a non-cornercondition is 115 psf, while the ultimate load requirement for Wind ZoneIII for a corner condition is 145 psf.

Example 2

Negative wind pressure load tests were conducted on samples of 48″×90″Sheathing 1 (described above in Example 1). The following describes thetest specimens that were used in Example 2.

Example 2 Specimen Description

A. Materials

-   -   1. Stud: 2×4, Stud Grade SPF spaced at 16″ o.c.    -   2. Top Plate: Single 1×4, Ungraded SPF    -   3. Bottom Plate: Single 1×4, Ungraded SPF    -   4. Gypsum: 5/16″×48″×90″ Gypsum, Georgia-Pacific    -   5. Siding: Georgia Pacific 4.5 Lap Vinyl Siding with a nailing        flange thickness of 0.036 inch    -   6. Adhesive: PVA

B. Fastening

-   -   Top plate attached to studs with three (3)- 7/16″×1¾″×15 Ga.        Staples.    -   Bottom plate attached to studs with three (3)- 7/16″×1¾″×15 Ga.        Staples. * Sheathing 1 fastened with 1″×1½″×16 Ga. staples at 3″        o.c. on framing members.    -   Gypsum fastened to studs with 3/16″×1″×19 Ga. Staples at 16″        o.c. per strip of siding.    -   Gypsum glued to frame with a ⅜″ bead of PVA glue on all framing        members.    -   Siding fastened to sheathing into the studs with 7/16″×1½″×16        Ga. staples at 16″ o.c. per strip of siding.

C. Construction

The construction was similar to that described above in Example 1.

Example 2 Test Setup and Procedure

The test setup and procedure were similar to that described above inExample 1.

Example 2 Results

Three specimens (S1, S2, S3) using 5/16″ Georgia-Pacific Gypsum weretested for non-comer Wind Zone III requirements. The results are asfollows in Table 2. TABLE 2 ULTIMATE EXPER. LOAD (PSF) AVG. DEFLECTIONNO. S1 S2 S3 (PSF) (PASS/FAIL) WINDZONE 2 135.2 140.4 135.2 136.9 PASSEDIII Non- Corner

The samples in Experiment 2 passed the requirement for ultimate loadunder a non-comer condition for Wind Zone III. In addition, the samplesin Experiement 2 also passed the deflection test under a non-comercondition for Wind Zone III.

While the present invention has been described with reference to one ormore particular embodiments, those skilled in the art will recognizethat many changes may be made thereto without departing from the spiritand scope of the present invention. Each of these embodiments andobvious variations thereof is contemplated as falling within the spiritand scope of the claimed invention, which is set forth in the followingclaims.

1. A sheathing adapted to be fastened to at least one wall supportingstructure, comprising at least two layers: (a) a first layer comprisinga polymeric foam layer; (b) a second layer comprising a woven polymericscrim, said second layer being located adjacent to said first layer,wherein the polymeric scrim includes a first portion and a secondportion, the second portion being located near the periphery of thepolymeric scrim layer, the first portion having a first machinedirection scrim count number and a first transverse direction scrimcount number, the second portion having a second machine direction scrimcount number and a second transverse direction scrim count number, atleast one of the second machine direction scrim count number and thesecond transverse direction scrim count number being greater than therespective first machine direction scrim count number or the firsttransverse direction scrim count number; (c) an adhesive located betweensaid first and said second layers; and (d) a third layer comprising animpact polystyrene, said first layer being located between the adhesiveand said third layer.
 2. The sheathing of claim 1, wherein the polymericscrim includes a third portion, the third portion being located near theperiphery of the polymeric scrim layer opposite the second portion, thethird portion having a third machine direction scrim count number and athird transverse direction scrim count number, at least one of the thirdmachine direction scrim count number and the third transverse directionscrim count number being greater than the respective first machinedirection scrim count number or the first transverse direction scrimcount number.
 3. The sheathing of claim 2, wherein the second and thirdmachine direction scrim count numbers are the same.
 4. The sheathing ofclaim 2, wherein the second and third transverse direction scrim countnumbers are the same.
 5. The sheathing of claim 2, wherein the secondand third portions are located generally parallel to the at least onewall supporting structure.
 6. The sheathing of claim 2, wherein thesecond and third machine direction scrim count numbers are the same andthe second and third transverse direction scrim count numbers are thesame.
 7. The sheathing of claim 1, wherein the second machine directionscrim count number is at least about two times the first machinedirection scrim count number.
 8. The sheathing of claim 2, wherein thesecond and third machine direction scrim count numbers are at leastabout two times the first machine direction scrim count number.
 9. Thesheathing of claim 1, wherein the second machine direction scrim countnumber is at least about four times the first machine direction scrimcount number.
 10. The sheathing of claim 2, wherein the second and thirdmachine direction scrim count numbers are at least about four times thefirst machine direction scrim count number.
 11. The sheathing of claim1, wherein the second machine direction scrim count number is at leastabout six times the first machine direction scrim count number.
 12. Thesheathing of claim 2, wherein the second and third machine directionscrim count numbers are at least about six times the first machinedirection scrim count number.
 13. The sheathing of claim 1, wherein thethickness of the sheathing is from about 0.25 inch to about 3 inches.14. The sheathing of claim 2, wherein the second and third portionsextend from the periphery of the polymeric scrim layer inwardly about 2to about 3 inches.
 15. The sheathing of claim 1, wherein the first layeris a polyethylene terephthalate foam.
 16. The sheathing of claim 1further including a fourth layer comprising an impact polystyrene, saidfourth layer being located adjacent to said first layer and said firstlayer being located between said third and said fourth layers.
 17. Thesheathing of claim 16 further including a polymeric film layer, saidthird layer located between said first layer and said polymeric filmlayer.
 18. The sheathing of claim 1, wherein said impact polystyrene isa high impact polystyrene.
 19. The sheathing of claim 1 furtherincluding a polymeric film layer, said third layer located between saidfirst layer and said polymeric film layer.
 20. The sheathing of claim 1,wherein said polymeric foam is a polyolefin foam.
 21. The sheathing ofclaim 1 wherein said polymeric foam is a polystyrenic foam.
 22. Thesheathing of claim 1, wherein said polymeric scrim is a polypropylenescrim.
 23. The sheathing of claim 1, wherein said polymeric scrim is apolyolefin scrim.